Tutorial 1 - Jan 9-13 2017 Work in groups of 3 at the blackboards. Do the questions in order and, when you complete each question, write it down. If in doubt, ask your TA for help. Exchange roles - i.e. don't have the same person writing on the blackboard - cooperate! Student 1: UBC#: Name: Student 2: UBC#: Name: Student 3: UBC#: .Name: Problem 1 Two identical conducting spheres (1 and 2 in the figure) are held in place 20cm apart. They are initially charged with Q1 = 5pC and Q2 = 3,C. A third sphere, identical to the first two and initially neutral, is brought to contact first with sphere 2, then with sphere 1 and is finally taken away. What is the final electric force between spheres 1 and 2? Is it repulsive or attractive? After step 1 : Q1= 5MC Q2=Q3 = 1.5m /C Q=5 uC 1 20 cm 1 1 Q =? 20 cm Q = 3 HC 2 2 Q =? 2 After step 2 : Q1 = Q3 = 3,25 ML Q2 = 1,5 Ml Force : F = K Q1Q2 = r2 8.9x10x 3.25x10% 6 1.5x 10-6 N 0.22 F = 1.08 N 1 Force is repulsive
Problem 2 Three charges are placed in the corners of a rect- angle as shown. A particle of charge 3nC and mass 2g is then placed in the top left corner of the rectangle. a) What are the x and y components of the force acting on it? b) What are the components of its acceleration? What is the magnitude of the acceleration? - 18 Rx 15x10 a) F = 1 J (2 x 10-2)2 10 nC 92 4 cm + 1 1 2 cm - -5 nC 91 F2 = = kx 30x10- -18 (4x10-2)2 1 F = k x 30x10 -18 [??+??] (2.2+42) x 10-4 É net 10 nC 93 -18 N + Rx30x10 1, 5 1 2 + - 4×10-4 7 TIL = (-2.86 1 - 2,74 [ ) x 10 4 N net b) à = Fret =(-0.1431-0.137 M 1 52 2 12']= (0,143)+(0.137)2 M 53 = 0.198 52 - M